Among the various types of organopolysiloxanes already known in the art, MQ organopolysiloxanes composed of monofunctional siloxane units (M units) and tetrafunctional siloxane units (Q units) (refer to Japanese Patent Application Laid Open Number Sho 61-195129 (U.S. Pat. No. 4,707,531) are used as starting material for varnishes and pressure-sensitive adhesives because of their heat resistance. More recently, hydroxyphenyl-containing MQ organopolysiloxane has been taught by Japanese Patent Application Laid Open Number Hei 1-292036 (U.S. Pat. No. 4,946,921) and chloromethyl-containing MQ organopolysiloxane has been taught by Japanese Patent Application Laid Open Number Hei 2-153935. The present inventor has also already proposed MQ organopolysiloxanes that contain epoxy-functional organic and alkoxysilylalkyl groups (Japanese Patent Application Laid Open Number Hei 5-105758 (U.S. Pat. No. 5,310,843)) and MQ organopolysiloxanes that contain epoxy-functional organic groups and diorganopolysiloxane residues (Japanese Patent Application Number Hei 3-331409 (U.S. Pat. No. 5,283,309)).
However, MQ organopolysiloxane in which epoxy-functional organic and C.sub..gtoreq.6 alkyl groups are present on the monofunctional siloxane unit (M unit) silicon has heretofore been unknown.